1. Field of the Invention
The present disclosure relates to a thin film transistor substrate and a method for fabricating the same, which can shorten a process time, prevent scratches from taking place at an alignment film, and increase black luminance.
2. Discussion of the Related Art
In general, a liquid crystal display device controls light transmissivity by using an electric field for displaying a picture. The liquid crystal display device is provided with a thin film transistor substrate and a color filter substrate faced each other with liquid crystals placed therebetween.
The thin film transistor substrate has gate lines and data lines formed perpendicular to each other, a thin film transistor formed at every crossed portion of the gate lines and data lines, a pixel electrode connected to each of the thin film transistors, and a lower alignment film coated thereon for alignment of the liquid crystals.
The color filter substrate has color filters for producing colors, a black matrix for preventing a light from leaking, a common electrode for forming an electric filed with the pixel electrode, and an upper alignment film coated thereon.
Referring to FIG. 1, a related art alignment film 14 is formed as a rubbing roller 12 having a rubbing cloth 10 wound thereon rolls on organic polymer on a substrate 16 to rub the substrate 16.
When the alignment film 14 is brought into contact with the rubbing cloth 10 thus, foreign matters or static electricity are produced at a contact portion thereof. If such foreign matters are left on the alignment film 14, defects, like stains, take place on a screen, and the static electricity can break neighboring thin films and thin film transistors.
Moreover, alignment of the liquid crystals becomes non-uniform at a region of the alignment film 14 at which scratches are formed by the rubbing cloth 10, and a region the contact of the rubbing cloth 10 to the alignment film 14 is failed due to steps caused by a plurality of thin films under the alignment film 14. Consequently, leakage of light takes place to increase a black state luminance, making contrast of the liquid crystal display device poor.
Furthermore, in a case of a large sized panel, control of uniform rotation of the rubbing roller 12 is difficult, making obtaining uniform alignment of the liquid crystals difficult.